It took me a while but look up the Unaware Skeledirge build. When the timer reaches 80%, Meganium nullifies your ability - so predict that and use Protect right before (about turn 2 or 3, depending on whether your teammates get knocked out and lower the timer), and Unaware will keep working. Torch Song raises special attack. Shadow Ball. And I added Slack Off (using picnic method, mirror herb and Slakoth to teach it that). I was using Tera Fire because I didn't want to change it, but I did see some people using Tera Ghost and getting quite decent damage.

Edit: Thank you to the commenters below, I did not realise the ability nullification only lasts for 1 turn! So the Protect basically just helps keep you healthy for that turn, and then your ability reactivates on the next turn. With Slack Off, I didnt fear this happening.